1. Field of the Invention
The present application is directed to a family of resettable circuit interrupting devices that includes Ground Fault Circuit Interrupters (GFCI's) and more particularly to GFCI'S which detect and interrupt the electrically conductive paths between the line side and a load side terminals of the GFCI upon detection of a voltage on the ground conductor of the GFCI.
2. Description of the Related Art
The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to automatically interrupt power to a load, such as a household appliance, a consumer electrical products and/or a branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with Ground Fault Circuit Interrupters (GFCI). Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894, which is incorporated herein in its entirety by reference, use a trip mechanism to break an electrical connection between the line side and the load side terminals of the device. Such devices are resettable after they are tripped by, for example, the detection of a ground fault. In the device discussed in the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the conductive path between the line side terminals and the load side terminals) includes a solenoid (or trip coil). A test button is used to both test the trip mechanism and the circuitry used to sense faults, and a reset button is used to reset the electrical connection between line and load side terminals.
Commonly owned U.S. Pat. No. 6,282,070 which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists and is capable of breaking electrical conductive paths independent of the operation of the circuit interrupting portion. Such devices are connected to external wiring so that phase and neutral line wires are connected to the phase and neutral line side connections and the phase and neutral load side wires are connected to the phase and neutral load side connections. In addition, in installations where there is a ground wire, the ground wire is connected to the ground terminal on the GFCI. When an installer connects a GFCI to a two-wire system, the installer will normally first connect the neutral terminal on the GFCI to the neutral wire and the phase terminal of the GFCI to the phase wire. However, instances may occur where the ground terminal of the GFCI is not properly connected to the grounding conductor of the electrical system and could be connected to the hot conductor instead. This mis-wiring may occur through a mistake by the installer at the receptacle or by a wiring error in the building system itself. For example, when the building was first wired, the color coding of connecting the black wire to the phase of the power source and the white wire to neutral or ground of the power source was not followed. If the installer does not verify that the building is wired correctly, as should be done with any electrical installation, the latter may occur. If a person inserts a three-wire plug of an appliance with a grounded metal case into the receptacle on the GFCI, the shell of the appliance will be connected to 120 volts through the grounding wire. Since, by the NEC code requirement, the grounding wire is never interrupted by any wiring device including a GFCI, the potential exists that a user of the appliance can be severely shocked. What is needed is a GFCI which will trip when the grounding conductor is connected to a voltage source.